Biden kicks-off three-nation visit ahead of Nato summit in Lithuania

US President Joe Biden left for a three-nation trip that will be dominated by a NATO summit to show support for Ukraine despite tensions about Kyiv's potential membership in the alliance, Al Jazeera reported.

Late on Sunday, Biden flew from Delaware's Dover Air Force Base to the United Kingdom, a crucial US ally.

The US president will hold a meeting with King Charles of the UK on Monday for the first time since his coronation, according to the White House, to discuss environmental issues.

At 10 Downing Street, Biden will also have a meeting with Prime Minister Rishi Sunak. The impending NATO summit and Ukraine are likely to come up for discussion during their meetings, according to Sunak's spokesperson.

"As we face new and unprecedented challenges to our physical and economic security, our alliances are more important than ever," Sunak said in a statement released by his office on Saturday.

"The UK is Europe's leading NATO ally, we are the United States' most important trade, defence and diplomatic partner, and we are at the forefront of providing Ukraine with the support they need to succeed on the battlefield," he added, as per a report published in Al Jazeera.

The main focus of Biden's travel to Europe will be the NATO summit taking place Tuesday and Wednesday in the capital of Lithuania, where the Western partners will debate aiding Ukraine in driving out invading Russian forces.

After Ankara accused Stockholm of being too indulgent towards groups it views as a security danger, including Kurdish armed groups and individuals linked to a 2016 coup attempt, Biden is expected to use the summit to pressure Turkey into withdrawing its opposition to Sweden's NATO membership bid.

During a telephonic conversation with Turkish President on Sunday, "Biden conveyed his desire to welcome Sweden into NATO as soon as possible," said the White House.

The statement added that the two leaders "expressed their shared commitment to continue supporting Ukraine."

Erdogan will meet Biden on the sidelines of the NATO summit, said his the Turkish president's office.

The discussion between the two will emphasise on "Ukraine's positon in NATO, Sweden's NATO membership, and the delivery of F-16 fighter jets," which Turkey hopes to secure from the United States, the Turkish presidency said.

Prior to departing the country, Biden stated that he would reject requests for giving Ukraine quick entry into the alliance--a proposal that Erdogan publicly backed on Saturday, as per Al Jazeera.

All 31 members must agree unanimously for a country to join NATO. At this week's summit, Ukraine has demanded that the military alliance lay out a clear path for membership. However, the US and Germany have expressed strong reluctance about the prospect of welcoming a country at war with unfinished democratic reforms, insisting that the priority should be on providing weapons and ammunition.

"I don't think there is unanimity in NATO about whether or not to bring Ukraine into the NATO family now, at this moment, in the middle of a war," Biden said in a CNN interview previewing his trip.

He appealed caution, saying the alliance could get drawn into the war with Russia due to NATO's mutual defence agreement.

NATO could take decision to elevate its ties with Ukraine, creating what would be known as the NATO-Ukraine Council and giving Kyiv a seat at the table for consultations, reported Al Jazeera.